Aspect ratio refers the ratio of a width (W) of an image or to a height (H) of the image, or W:H. For most conventional televisions, the aspect ratio is 4:3. In the case of high definition television (HDTV), most have an aspect ratio of 16:9. Notwithstanding, the aspect ratio and the number of vertical scan lines in the image may determine an appropriate sample rate that should be utilized to digitize the video image.
Aspect ratio accommodation refers to presentation of an image having a first native aspect ratio in a second non-native aspect ratio. Various techniques have been developed to facilitate aspect ratio accommodation, some of which may include blanking adjust, truncation, pan and scan, anamorphic squeeze, and shoot and protect. While blanking adjust and shoot and protect may maintain a director's intent during aspect ratio accommodation, truncation, pan and scan, and anamorphic squeeze does not maintain a director's intent. Truncation, pan and scan, anamorphic squeeze and shoot and protect utilizes full screen, but blanking and adjust does not utilize full screen. Blanking adjust, anamorphic squeeze, and shoot and protect may display all action, but truncation and pan and scan may not display all action.
Blanking adjust, truncation, pan and scan, and shoot and protect may maintain picture geometry during aspect ratio accommodation, but picture geometry is not maintained in anamorphic squeeze. Automatic conversion may be done with blanking adjust, truncation, anamorphic squeeze, and shoot and protect, but automatic conversion is not possible with pan and scan. Full freedom production may be achieved with blanking adjust, truncation, pan and scan, and shoot and protect, but full production freedom is not possible with anamorphic squeeze.
A letterbox image is an image in which about three-quarters of the vertical picture height has been limited so that a wider aspect ratio may be achieved. Accordingly, the image has be reduced to a letter or letterbox size and hence the name letterbox. Currently, no clear requirement exists for letterbox detection (LBOX), and at best, conventional letterbox detection may best be described as “count black lines.”
Center cut, also called center cut out, or CCO, refers to an aspect ratio correction performed by cropping a region from the source stream. This is similar to “pan and scan” utilized in DVDs, for example. Square scaling, also called aspect ratio correct scaling, refers to instances where an image is scaled equally in the X and Y directions. Square scaling does not change the aspect ratio. Non-square scaling, also called aspect ratio incorrect scaling, refers to instances where an image is scaled disproportionately in the X-axis and Y-axis directions. A non-square scaling may be implemented as an anamorphic scaling, or a non-linear scaling, or any other disproportionate method. However, non-square scaling results in a change in the aspect ratio.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.